Carbamyltriazole insecticides

ABSTRACT

Insects of the orders Diptera, Coleoptera, Orthoptera and Lepidoptera are killed in the presence of living plants by applying to the locus of the insects an effective amount of a compound having the structural formula ##STR1## in which R is 2-propynyl, allyl, 2-bromoallyl, 2-chloroallyl, 2-methylallyl, 1-methylallyl or 2,3,3-trichloroallyl and R&#39; is tert.butyl, propyl, cyclopropyl, isopropyl or 1-methylpropyl.

DESCRIPTION OF THE INVENTION BACKGROUND OF THE INVENTION

U.S. Pat. No. 3,308,131 discloses a class of compounds, said to beuseful as insecticides, having the general structural formula ##STR2##Compounds in which there is aliphatic unsaturation in R³ or R⁴ arespecifically excluded from the disclosed class. It is true that some ofthe specifically excluded compounds are virtually useless asinsecticides. One example is the compound1-N,N-dimethylcarbamyl-3-cyclohexyl-5-propargylthio-1,2,4-triazole.Similar compounds with a trifluoromethyl substituent in 3-position arealso generally lacking in insecticidal activity of any practicalimportance.

However, I have discovered a restricted group of highly active, usefulinsecticides among those excluded from the aforementioned patent whichhave the general structural formula ##STR3## in which R is 2-propynyl,allyl, 2-bromoallyl, 2-chloroallyl, 2-methylallyl, 2,3,3-trichloroallyl,or 1-methylallyl and R' is tert.butyl, propyl, cyclopropyl, isopropyl or1-ethylpropyl.

SUMMARY OF INVENTION

Briefly, my invention is the method of selectively killing insects ofthe orders Diptera, Coleoptera, Orthoptera and Lepidoptera in thepresence of living plants comprising applying to the locus of theinsects an effective amount of a compound having the structural formula##STR4## in which R is 2-propynyl, allyl, 2-bromoallyl, 2-chloroallyl,2-methylallyl, 1-methylallyl or 2,3,3-trichloroallyl and R' istert.butyl, propyl, cyclopropyl, isopropyl or 1-methylpropyl. Themethods of manufacturing and use of the novel insecticides areillustrated specifically in the detailed description which follows.

DETAILED DESCRIPTION

The insecticide is conveniently prepared on a laboratory scale by meansof the procedures described below.

Preparation of 3-tert.butyl-4H-1,2,4-triazolin-5-thione

To a suspension of 50 g (0.55 mol) of thiosemicarbazide and 43 g (0.05mol) of pyridine in 300 ml of dioxane was added 42.6 g (0.6 mol) ofpivalyl chloride, with cooling. The reaction was stirred at roomtemperature for 72 hours, then poured into water. The resulting solidwas collected, washed with water and dried. The unpurified pivalylthiosemicarbazide was heated at reflux temperature in 300 ml of 10%sodium hydroxide solution for 3 hours. After cooling, the pH wasadjusted to 4 with hydrochloric acid and the product collected, washedwith water and dried to give 43.8 g, m.p. 200°-203°. Recrystallizationfrom methanol-chloroform solvent mixture gave a sample, m.p. 203°-205°.

Preparation of 3-tert.butyl-5-allylthio-4H-1,2,4-triazole

To a suspension of 150 g (0.955 mol) of3-tert.butyl-4H-1,2,4-triazolin-5-thione in 1000 ml of ethanol was added121 g (1.0 mol) of allyl bromide. After stirring at room temperature for16 hrs, the reaction was heated at reflux temperature for two hrs, thenmost of the ethanol was removed at reduced pressure on the rotaryevaporator. Water was added to dissolve the precipitated solids and thesolution was taken to pH 9 with dilute NH₄ OH. The product precipitatedand was collected, giving 156.8 g. m.p. 127°-130°. Recrystallizationfrom ether-petroleum ether solvent mixture raised the melting point to131°-133°.

Preparation of1-Dimethylcarbamyl-3-tert.butyl-5-allylthio-1H-1,2,4-triazole

A solution of 56 g (0.284 mol) of3-tert.butyl-5-allylthio-4H-1,2,4-triazole and 31.2 g (0.29 mol) ofdimethylcarbamyl chloride in 300 ml of pyridine was maintained at refluxtemperature for 16 hrs. After the pyridine was removed at reducedpressure on the rotary evaporator, water was added followed bychloroform. The organic layer was washed with successive portions ofdilute hydrochloric acid, water and brine, then dried over Na₂ SO₄. Thesolvent was removed in vacuo to give 66.3 g of an oil, n_(D) ²⁶ 1.5126.

The compounds disclosed specifically below, as well as other compoundsof the class of the invention may be made from purchased raw materialsby means of the general procedures which are specifically exemplifiedabove.

Use of the Novel Insecticides

Use of the new insecticide is illustrated by means of controlled testsproviding a measure of efficacy on various species, according toprocedures described below.

Method for Mites, Aphids, Bean Beetles and Army Worms

Three 5 oz paper cups containing Henderson dwarf lima bean plants andone 5 oz paper cup containing Orange Gem nasturtiums, all growing invermiculite, are placed on a turntable and sprayed to thorough wetnesswith 25 ml of a solution of the candidate chemical at the appropriateconcentration. Nasturtiums were already infested with 50-100 bean aphids(BA). A bean plant in one paper cup was already infested with 50-100two-spotted mites (TSM). Leaves from the two remaining bean plants areremoved following spraying and placed in disposable petri dishes with 5southern armyworm (SA) larvae in one petri dish, and 5 Mexican beanbeetle (MBB) larvae in the other petri dish. The rating is doneapproximately 48 hours after spraying as follows:

    ______________________________________                                             BA                 TSM                                                   ______________________________________                                        0 = none dead      0 = no dead adults                                         1 = 1-25% dead     1 = 1-25% dead adults                                      2 = 26-50% dead    2 = 26-50% dead adults                                     3 = 51-75% dead    3 = 51-75% dead adults                                     4 = 76-99% dead    4 = 76-99% dead adults                                     5 = 100% dead      5 = 100% dead adults                                       ______________________________________                                             MBB                SA                                                    ______________________________________                                        0 = no larvae dead 0 = no larvae dead                                         1 = 1 -25% larvae dead                                                                           1 = 1-25% larvae dead                                      2 = 26-50% larvae dead                                                                           2 = 26-50% larvae dead                                     3 = 51-75% larvae dead                                                                           3 = 51-75% larvae dead                                     4 = 76-99% larvae dead                                                                           4 = 76-99% larvae dead                                     5 = 100% larvae dead                                                                             5 = 100% larvae dead                                       ______________________________________                                    

Method for Southern Corn Rootworm (SCR)

Three 5 oz paper cups planted each with one kernel of DeKalb XL-361 cornare treated two days after planting with 10 ml of a 125 ppm solution ofthe candidate compound. Compounds with high efficacy are treated atlower concentrations. The experiment is a 4×5 factorial in a randomizedcomplete block design with three replications. The tests are evaluatednine days after treatment. The roots are inspected under a dissectingmicroscope and rated as follows:

    ______________________________________                                        SCR Rating       % root feeding damage                                        ______________________________________                                        5                 0                                                           4                 1-25                                                        3                26-50                                                        2                51-75                                                        1                76-99                                                        0                100                                                          ______________________________________                                    

So as to obtain more meaningful results, all tests are performed at thesame time of day, whenever possible, usually in the forenoon.Temperature, illumination and humidity are the same in all tests.Atmospheric pressure is not controlled.

Results obtained with the novel insecticides of this invention atvarious concentrations of active chemical are tabulated below. Theratings given are for averages of three or more replicates. The orallethal dose for 50 percent kill of laboratory rats is also recorded inthe table. In conducting the toxicity tests on rats, 0.01 g of activechemical per ml in corn oil is employed as an additive to the diet ofthe animals.

    __________________________________________________________________________    RESULTS OF INSECTICIDAL USE OF COMPOUNDS OF THE FORMULA                        ##STR5##                                                                                PHYS.       CONCENTRATION (ppm)                                    COMPOUND  PROPERTIES                                                                             Species                                                                           500                                                                              250                                                                              125                                                                              100                                                                              62                                                                              50                                                                              31                                                                              25                                                                              15                                                                              12                                                                              8 6 4 3 2 Remarks              __________________________________________________________________________                       MBB 5  5  5     3   1   1                                  R=2-propynyl                                                                  (propargyl)                                                                             n.sub.D.sup.26 = 1.5585                                                                SA  5  4  2     0   0   0             LD.sub.50                               BA  5  5  5     5   5   5   5   3   1 10 mg/kg             R'=cyclopropyl     TSM 5  4  4     2   0   0                                                     SCR          4.3  4.3 1.3 0   0   0                                           MBB 5  5  5     5   4   0                                  R=2-propynyl       SA  5  5  3     0   0   0                                            n.sub.D.sup.26 = 1.5286                        LD.sub.50            R'=isopropyl       BA  5  5  5     5   5   5   2   3   0 approx.                                 TSM 0                                 50 mg/kg                                SCR          4    2.7 1.3 0.3 0   0                                           MBB 5  5  5     3   1   0                                                     SA  5  0  0     0   0   0                                            n.sub.D.sup.26 =1.5242                                              R'=propyl          BA  5  5  5     5   5   5   1   0   0                                         TSM 0                                                                         SCR          3.7  2.7 1.3 0   0   0                        R=-2-bromo-        MBB 2                                                      propenyl                                                                      (2-bromoallyl)                                                                          n.sub.D.sup.26 = 1.5455                                                                SA  0                                                                         BA  5  5  5     5   4   2   0                              R'=cyclopropyl     TSM 2                                                                         SCR          4.3  0.3 0   0   0   0                                           MBB 5  5  5     1   0   0                                  R=2-propenyl                                                                  (allyl)   n.sub.D.sup.26 =1.5126                                                                 SA  1                                 LD.sub.50                               BA  5  5  5     5   5   5   4   3   2 17 mg/kg             R'=tert.butyl      TSM 0                                                                         SCR          4    3   2.5     1                                               MBB 5  5  5     5   5   4   0   0                          R=2-propynyl       SA  5  5  2     0   0   0             LD.sub.50 >          R'=tert.butyl                                                                           n.sub.D.sup.26 =1.5212                                                                 BA  5  5  5     5   5   5   5   5     50 mg/kg                                TSM 1                                                                         SCR          4    5   5   4.5 3.5 2                        R=2-bromo-         MBB 2                                                      2-propenyl                                                                                       SA  0                                                      (2-bromoallyl)                                                                          m.p. 52°-56° C.                                                          BA  5  5  5     5   5   5   4   4                          R'=tert.butyl      TSM 4  0  0     0   0   0                                                     SCR          0                                                                MBB 5  5  5     2   0   0                                  R=2-propenyl                                             LD.sub.50            (allyl)   n.sub.D.sup.26 =1.5175                                                                 SA  5  0  0     0   0   0             between              R'=isopropyl       BA  5  5  5     5   5   5   4   2   0 10 and                                  TSM 0                                 50 mg/kg                                SCR          4    4   4   4   4   3.5                                         MBB 5  5  2     0   0   0             LD.sub.50            R=2-propenyl                                                                  (allyl)   n.sub.D.sup.26 = 1.5373                                                                SA  5  0  0     0   0   0             between              R'=cyclopropyl     BA  5  5  5     5   5   5   5   5   4 5 and                                   TSM 5  5  5     3   0   0             10 mg/kg                                SCR          5    3.5 3.0 2.5 2.5 3.0                                         MBB 2                                                      R=2-methylallyl                                                                                  SA  0                                                                liquid                                                              R'=tert.butyl      BA  5  5  5     5   5   5   4   4   1                                         TSM 0                                                                         SCR          1.3                                                              MBB 2                                                      R=2-chloroallyl                                                                         liquid   SA  0                                                      R'=tert.butyl      BA  5  5  5     5   5   5   4   4   4                                         TSM 0                                                                         SCR          1                                             R=2,3,3-trichloro- MBB 0                                                      allyl                                                                                   m.p. 62°-67°                                                             SA  0                                                      R'=tert.butyl      BA  4  5  5     5   5   5   4   3   3                                         TSM 0                                                                         SCR                                                        R=1-methylallyl    MBB 5  1  1     0   0   0                                            liquid   SA  4  0  0     0   0   0                                  R'=tert.butyl      BA  5  5  5     5   5   5                                                     TSM 0                                                                         SCR                                                        __________________________________________________________________________

it will be realized by workers in the art that the efficacy of theinsecticides at low concentration levels makes it advisable to combinethe compounds with inert carriers, according to conventional practice.In this way the compounds may be distributed more uniformly at desiredconcentration levels. Water is the most convenient inert carrier in manysituations and it is conventional practice to use commercial emulsifiersand dispersing agents so as to easily obtain uniform dispersions inwater for spray application. For use against soil-borne insects, drygranular combinations of insecticides with solid inert carriers may bepreferred, according to the common practice in the art.

It is only necessary to apply the insecticides to the zone in which theinsects live, or locus of the insects. Normal activity of the insectswill assure adequate contact with the insecticides, so that they neednot be applied directly to the insects.

I claim:
 1. The method of killing aphids in the presence of livingplants comprising applying to the locus of the aphids an aphicidallyeffective but substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-cyclopropyl-5-(2-propynylthio)-1H-1,2,4-triazole.2. The method of killing aphids in the presence of living plantscomprising applying to the locus of the aphids an aphicidally effectivebut substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-isopropyl-5-(2-propynylthio)-1H-1,2,4-triazole.3. The method of killing aphids in the presence of living plantscomprising applying to the locus of the aphids an aphicidally effectivebut substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-propyl-5-(2-propynylthio)-1H-1,2,4-triazole.4. The method of killing aphids in the presence of living plantscomprising applying to the locus of the aphids an aphicidally effectivebut substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-tert.butyl-5-allylthio-1H-1,2,4-triazole. 5.The method of killing aphids in the presence of living plants comprisingapplying to the locus of the aphids an aphicidally effective butsubstantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-tert.butyl-5-(2-propynylthio)-1H-1,2,4-triazole6. The method of killing aphids in the presence of living plantscomprising applying to the locus of the aphids an aphicidally effectivebut substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-isopropyl-5-allyl-thio-1H-1,2,4-triazole. 7.The method of killing aphids in the presence of living plants comprisingapplying to the locus of the aphids an aphicidally effective butsubstantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-cyclopropyl-5-allyl-thio-1H-1,2,4-triazole.8. The method of killing aphids in the presence of living plantscomprising applying to the locus of the aphids an aphicidally effectivebut substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-cyclopropyl-5-(2-bromoallylthio)-1H-1,2,4-triazole.9. The method of killing aphids in the presence of living plantscomprising applying to the locus of the aphids an aphicidally effectivebut substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-tert.butyl-5-(2-bromoallylthio)-1H-1,2,4-triazole.10. The method of killing corn rootworms in the presence of living cornplants comprising applying to the locus of the corn rootworms aninsecticidally effective but substantially non-phytotoxic amount of1-(N,N-dimethylcarbamyl)-3-tert.butyl-5-allylthio-1H-1,2,4-triazole.